Simple Procedure for writing Lewis Structures of allene C3H4 -Ex. #14 | Chemistry Net

Simple Procedure for writing Lewis Structures of allene C3H4 -Ex. #14

A simple procedure for writing Lewis structures is given in a previous article entitled “Lewis Structures and the Octet Rule”. Relevant worked examples were given in the following articles: Examples #1, #2, #3 , #4, #5, #6,  #7 #8, #9, #10, #11, #12 and #13.

Another example  for writing Lewis structures following the above procedure is given bellow:

Let us consider the case of allene (C3H4). Allenes have proven themselves to be valuable building blocks toward complex molecular targets, revealing novel applications in natural product synthesis, pharmaceutical chemistry and material science. The ongoing interest in allene chemistry results in a variety of new methodologies and pathways for the synthesis of allenes.

Step 1: Connect the atoms with single bonds

Easy method for constructing Lewis electron dot structures (step 1)
Fig. 1: Connecting the allene atoms with single bonds (step 1)
Step 2: Calculate the # of electrons in π bonds (multiple bonds) using  formula (1) in the article entitled “Lewis Structures and the Octet Rule”.:
Where n in this case is 3 (exclude the H atoms)
Where V = (4 + 2 + 4 + 4+ 2) = 16  
Therefore, P = 6n + 2 – V = 6 * 3 + 2 – 16 = 4   So there are 4 π electrons in  C3H4Therefore, 2 double bonds or 1 triple bond must be added to the structure of Step 1.
Step 3 & 4: The Lewis structures for C3H4 are as follows:

Easy method for drawing Lewis structure for C3H4
Fig. 2: Lewis electron dot structure for the allene molecule C3H4

1 comment:

  1. please how can you use your formula to write Lewis' structure for NH4+(ammonium)